Windmills have been used for hundreds, if not thousands of years, for a variety of uses. Modern wind turbines typically utilize one or more blades coupled to a rotor, which convert the kinetic energy of wind into mechanical energy as the rotor is turned by the wind. The blades typically range in length from about 65 to 130 feet (20 to 40 meters) or more. Although these wind turbines can create energy without the need for fossil fuels, they suffer from a number of disadvantages, including: (a) high initial costs including transportation of the blades and other components; (b) high costs and time required for maintenance due to their often large dimensions; (c) inability to operate in high wind conditions (e.g., above 25 mph); (d) inability to quickly adapt to changing wind directions; (e) need for a motor to rotate and thereby redirect the turbine as the wind direction changes; (f) need for large amounts of unobstructed space; and (g) locations often being far away from where the energy will be used.
U.S. Pat. No. 4,365,929 to Retz, U.S. Pat. No. 4,935,639 to Yeh, and U.S. Pat. No. 7,329,965 to Roberts et al. discuss vertical-axis wind turbines that have multiple wind channels disposed about a rotor and blades in order to direct the wind against the blades. Retz, Roberts, and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. However, these turbines do not allow the wind channels to pivot as a function of the wind direction.
U.S. Pat. No. 4,070,131 to Yen discusses a wind turbine having a plurality of vanes surrounding a rotor, which allow wind to enter the turbine between the vanes. Yen contemplates that the vanes can be pivotable with respect to the turbine structure. However, the vanes are open and closed electronically, which adds complexity to the turbine and reduces the power produced.
It is known to have a plurality of baffle panels that are disposed about a rotor, as described in U.S. Pat. No. 4,725,194 to Bartsch. However, the baffle panels are configured to prevent wind from accessing the windmill once the wind reaches a predetermined velocity, and are not used to direct wind against the windmill's rotor.
U.S. Pat. No. 6,962,478 to Tsipov discusses a vertical axis windmill having a turbine and a plurality of movable gate elements that direct airflow within the windmill. However, the gate elements can be opened as a function of the wind flow within the windmill, and thus allow wind within the windmill to escape through the gate elements, rather than retain the wind within the windmill. The Tsipov windmill is disadvantageous in that it is not efficient in capturing the energy from the wind.
U.S. Patent Appl. No. 2009/0066088 to Liang and U.S. Patent Appl. No. 2009/0315332 to Sheikhrezai discuss improved vertical axis wind turbines. However, these turbines are disadvantageous because they fail to include a plurality of vanes disposed about the blades to thereby direct wind against the blades.
Thus, there is still a need for wind turbine that can (a) immediately adapt to changes in wind direction without the use of motors, and (b) operate in low and high wind conditions.